When panel materials are to be joined together by spot welding, those panel materials are fixed by a clamping apparatus. For example, a car body is produced by assembling a plurality of panel materials, each of which constitutes the car body, using a joining means such as spot welding. In assembling the car body, the plurality of panel materials are positioned on a welding stage and are joined together in a state of clamping them. As a car-body assembly method, there is a method in which panel materials are transferred to a production line formed by a plurality of welding stages, on each of which a clamping apparatus is disposed, through use of carrier devices such as conveyors or transfer trucks. In this case, other panel materials are transferred to the respective welding stages by the carrier devices, and both panel materials are positioned and clamped by the clamping apparatuses fixed onto bases of the welding stages and, in such a state, are joined together by welding devices. In this method, the other panel materials are joined, to the panel materials transferred by the carrier devices such as conveyors or transfer trucks, at the welding stages, and these panel materials are transferred by the carrier devices to the next welding stages for welding further other panel materials.
Meanwhile, as another car-body assembly method, Japanese Patent Laid-Open No. 4-283034 discloses a method in which panel materials are transferred using transfer trucks to which the clamping apparatuses are provided. In this case, the panel materials become fastened by the clamping apparatuses of the transfer trucks, and while the panel materials are moved by the transfer trucks to a car-body assembly line that is equipped with the welding stages arranged per predetermined interval, assembly work is done by spot welding etc. of the other panel materials at the respective welding stages. In this method, clamping components carry out opening and closing operations at the respective welding stages, and the final stage of the car-body assembly line and the first stage thereof are connected by a return line, whereby the transfer trucks are used in circulation.
In both of the methods, as the clamping apparatuses, the clamping components intended to be opened and closed by pneumatic cylinders are employed, and pipes and hoses for supplying compressed air for opening and closing the clamping components are arranged around the clamping apparatuses. For this reason, the pipes and hoses interfere with various apparatuses and appliances in some cases, and it is necessary to ensure sufficient spaces around the clamping apparatuses so as not to interfere with the apparatuses and appliances even if the pipes and hoses swing.
Especially, in the case of carrying out a mixed flow production to simultaneously produce a plurality of types and makes of vehicles in a single car-body assembly line, since a single unit of clamping component cannot clamp the plurality of panel materials, a plurality of clamping components are attached to the clamping apparatus depending on the types etc. of vehicles to be produced and the corresponding clamping components move to predetermined clamp positions in accordance with the types etc. of vehicles to be carried. Consequently, the plurality of clamping components are attached intensively to the clamping apparatus, and pneumatic cylinders for open/close-driving the respective clamping components are attached to the clamping apparatus in accordance with the number of clamping components. Therefore, it is necessary to attach many pipes and hoses to each clamping apparatus in order to supply the compressed air to respective pneumatic cylinders, and it is required to ensure sufficient spaces around the pipes etc., in order to prevent the pipes etc. from interfering with the apparatuses and appliances even if the pipes etc. swing depending on the opening/closing operations of the clamping components.
An object of the present invention is to provide a clamping apparatus in which pipes and hoses for supplying fluid to a clamp-arm opening/closing cylinder are arranged so as not to be exposed externally.
Another object of the present invention is to provide such a clamping apparatus that sufficient spaces can be ensured around it.
Another object of the present invention is to provide a clamping apparatus intended to supply fluid via internal flow paths to a clamp-arm opening/closing cylinder and a moving-block driving cylinder provided to a plurality of moving blocks, each of which is movable.